Giving oral back?

Hey, so I usually don't post on this but I've been with my boyfriend for 5years; been having sex for 3 and have a beautiful almost 2year old son together.. My question is he just started to go down on me maybe a week or two ago and now he's pressuring me to return the favor. I've never given head before as he's my first but I've never asked him to he did it on his own I just feel like I shouldn't be pressured or feel like I HAVE to do it just because he's doing it to me. Advice?